1. Field
Embodiments of the invention relate generally to a power supply circuit and a receiving apparatus.
2. Background Art
Switching DC-to-DC converters are used as small and high efficient power supplies because high efficient power supplies are required to reduce power dissipation of electric apparatuses. However, outputs of the DC-to-DC converters are superposed with ripple voltages due to switching, and have high level of noises.
On the other hand, Series regulators are used as low noise power supplies because small and low noise power supplies are required to extend functionality and performances. Series regulators are used also as power supply circuits in DC-to-DC converters (for example, refer to JP-A 2007-151322(Kokai)).
Furthermore, as a high efficient and low noise power supply, a power supply circuit configuring a cascade connection between a series regulator and an output of a DC-to-DC converter is also used.
Downscaling, increasing efficiency, and reducing noise are achieved by having a cascade connection between a series regulator and an output of a DC-to-DC converter. However, the aforementioned power supply has a problem of increasing power dissipation because a certain voltage difference between an input and output of the series regulator is required to operate the series regulator.